Underwater well completion system



Jan. 13, 1970 c. R. HUTCHISON 3,489,213

UNDERWATER WELL COMPLETION SYSTEM Original Filed Nov. 8, 1966 5 Shets-Sheet 1 F IG l N A W I I I I ll" IHIIHIIHHHHI ATTORNEYS 1970 c. R. HUTCHISON UNDERWATER WELL COMPLETION SYSTEM 5 Sheets-Sheet 2 Original Filed Nov. 8, 1966 9 89 wwS F'IEE I:

AT TORNE Y5 Jan. 13, 1970 c. R. HUTCHISON 3,489,213

UNDERWATER WELL COMPLETION SYSTEM Original Filed Nov. 8, 1966 5 Sheets-Sheet 3 INVENTOR. CARL R. HUTCHISON Jw. W G E. ATTORNEYS V I Jafi- 1970 c. R. HUTCHISON 3,489,213

UNDERWATER WELL COMPLETION SYSTEM Original Filed Nov. 8. 1966 5 Sheets-Sheet 4 FIB E INVENTOR. CARL R. HUTCHISON ATTORNEYS Jan. 13, 1970 c, Hu c so 3,489,213

UNDERWATER WELL COMPLETION SYSTEM Original Filed Nov. 8, 1966 5 Sheets-Sheet 5 FIE-LI? "76 INVENTOR.

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ATTORNEYS United States Patent O 3,489,213 UNDERWATER WELL COMPLETION SYSTEM Carl R. Hutchison, Houston, Tex., assignor to FMC Corporation, San Jose, Calif., a corporation of Delaware Original application Nov. 8, 1966, Ser. No. 592,864.

Divided and this application Apr. 18, 1968, Ser.

Int. Cl. E21b 7/12, 15/02 US. Cl. 166-5 4 Claims ABSTRACT OF THE DISCLOSURE This application is a division of applicants co-pending application Ser. No. 592,864, filed Nov. 8, 1966, now abandoned, and entitled Underwater Well Completion System.

This invention pertains to a system for completing an underwriter well. More specifically, this invention relates to a method for completing underwater, and entirely from a remote position, a well that has been drilled and cased with ocean-bottom suspension equipment, and to apparatus for use in carrying out this method.

Exploratory well drilling in off-shore locations has become a significant facet of the petroleum industry, and projections for the future indicate it will retain its irnportance in the world-wide quest for crude oil and natural gas. When an off-shore well is drilled for exploratory purposes and producible quantities of oil and/or gas are found, the well is either completed at that time or is abandoned, the latter usually on a temporary basis with the thought of reentry and completion, at a later date. An increasing number of off-shore wells are being drilled and cased with so-called ocean-bottom suspension (hereinafter referred to as OBS) equipment designed for suspending the casing at the ocean floor and then completing the well at the surface, for in many instances this procedure has been found desirable over other techniques for underwater well drilling, the chief one being cost.

When OBS wells are temporarily abandoned, all of the risers between the ocean floor and the surface are removed, to be replaced later when the well is completed at the surface. Such replacement caninvolve problems, especially in areas where weather and water conditions are apt to be uncertain and thus unsafe for diver assistance. Furthermore, when divers must be used the depth of the water is a limiting factor, even though all other conditions might be ideal. Other problems arise when an operator uses OBS equipment and then decides to complete the well at the bottom of the water, for this equip ment is not designed for bottom completions.

Accordingly, a general object of this invention is to provide a new system for completing underwater wells drilled and cased with OBS equipment.

Another object of this invention is to provide a new method for underwater completion of wells drilled and cased in the OBS manner, and then temporarily abandoned.

Another object of this invention is to provide a new method for completing OBS Wells at the floor of the ocean or other body of overlying water entirely by remote control from the surface.

3,489,213 Patented Jan. 13, 1970 Still another object of this invention is to provide improved apparatus for completing wells drilled and cased with OBS equipment.

A further object of this invention is to provide an improved casing packoff that can be run and set by remote control from the surface without the assistance of divers or use of hydraulic equipment.

A still further object of this invention is to provide an improved type of casing packoff that can be run and set in a remote location and then retrieved therefrom, all with conventional drilling equipment.

These and other objects and advantages of the present invention will become apparent from the following description, taken with the accompanying drawings, in which:

FIGURE 1 is a view in side elevation and partially in section of the body of a casing packotf according to this invention;

FIGURE 2 is an enlarged fragmentary view in side elevation and in section of the packotf body of FIGURE 1 and its mandrel, after it has been landed in an outer housing but before it is locked in place;

FIGURE 3 is a view like FIGURE 2, showing the packoif locked between the outer housing and an inner casing;

FIGURE 4 is a view in side elevation and partially in section of a type of wellhead that can be used in practicing this invention, installed on a well casing and with two packoffs of this invention locked in position between the wellhead and an inner casing string;

FIGURE 5 is a view in side elevation and partially in section, on a reduced scale, of the upper portion of the Wellhead of FIGURE 4 together with a Christmas tree installed on its upper end;

FIGURE 6 is a view in side elevation and partially in section of the lower portion of the wellhead of FIGURE 5, showing the connections between it and the several casing strings; and

FIGURE 7 is a view similar to FIGURES 5 and 6, showing the same well as it appeared when temporarily abandoned and before completion had begun according to this invention.

Broadly considered, the method of this invention comprises (a) running and landing a unitized wellhead on an outer casing string of the underwater OBS well at the general level of the floor of the body of water overlying the well; (b) extending the first inner casing string adjacent the outer string into the wellhead; (c) packing off the annulus between the wellhead and the first inner casing string; (d) repeating steps (b) and (c) on all remaining inner casing strings, in consecutive order from the outermost to the innermost; (e) running at least one production tubing string and landing it in the wellhead; and (f) running and landing a Christmas tree onto the wellhead and connecting it to the production tubing. Using apparatus of the type described later, this method can be carried out entirely by remote control from the surface without diver assistance, and thus the depth of the water overlying the well is not a limiting factor. Furthermore, although this method has been devised primarily for underwater completion of OBS wells that have been temporarily abandoned, it also can be employed to com plete new OBS wells, i.e'. those that have been drilled and cased, yet not abandoned.

As the drawings illustrate, the apparatus for carrying out this invention comprises a selection of connectors, casing extensions, landing subs and adapters, casing packoffs, production tubing, a tubing hanger, a hanger holddown, a unitized or integral wellhead, and a Christmas tree, all capable of assembly into a well-completion unit and attachment to an underwater well at a sub-surface )cation entirely by remote control. These various eleients are connected to the well and to one another by ianipulation of conventional well drilling equipment, articularly drill pipe and running tools, thereby obviating 1e need for special devices or techniques.

The packofis used in this completion system are espeially significant, both in the manner in which they are un and set, and in their cooperation with the wellhead provide access to the annuli between the casing strings or pressure monitoring. FIGURES 13 illustrate one JIIH of this type of packoff, and FIGURES 4-6 illustrate :vo additional forms, all of these forms embodying the ame principles of locking and sealing. Perhaps these perations can best be explained by a description of the ackofif of FIGURES 1-3, it being understood that the ame procedures are followed with the other packotfs of IGURES 4-6.

As illustrated in FIGURES l-3, the packoff comrises a generally elongated tubular body 12, a tubular iandrel 14 slidably circumscribed by the body 12, and plurality of locking dogs 16 slidably positioned in ports 8 that extend through, and are circumferentially spaced round, the body 12. The inner or bore surface 20 of the ody 12 contains an upper annular groove 22, a lower an- .ular groove 24, and an intermediate shoulder 26, the boulder 26 being of equal diameter with the aforesaid ore surface 20. A plurality of axially extending slots 28 xtend through the shoulder 26 and form a passageway etween the groove 22, 24, and tangentially adjacent the xtensions of the sides of the slots 28 are a plurality of adially inward projecting stop pins 30 and 32 (FIG. 1), he pins 30 tangentially adjacent an upward extension of 1e right-hand side 28a of the slots 28 when the body is iewed in its conventional upright position, and the pins 2 tangentially adjacent a downward extension of the aft-hand side 28b of the slots 28. As will be described ater, these grooves, slots, and pins cooperate with the 1andrel 14 in running and setting, and also in retrieving, he packoff.

As shown in FIGURES 2 and 3, the mandrel 14 has an .pper locking section with an outer surface 42 and an iner annular groove 44, a lower section 46 of smaller utside diameter than the locking section 40 and with a lurality of ears 48 projecting radially outward from its xternal surface 50, and an intermediate section 52 with n upwardly and outwardly extending camming surface i4.

When the body 12 and the mandrel 14 are assembled 1 the unlocked condition (FIG. 2), i.e., the condition a which the packoff 10 exists as it is being run into or etrieved from a well, the lower section 46 of the mandrel 4 opposes the locking dogs 16, and the ears 48 extend rito the upper groove 22 in the body 12. From this conition the packoff 10 can be set in a housing 56, Such as unitized wellhead of the type disclosed in the copending V. L. Todd US. patent application, Ser. No. 446,788, lled Apr. 2, 1965, now Patent No. 3,299,958 and assigned 9 the same assignee as the instant application, by rotating he mandrel 14 to the right (i.e., clockwise when viewed rom the top) until the ears 48 contact the stop pins 30, owering the mandrel until the ears 48 pass downward hrough the slots 28 into the lower groove 24 (FIG. 3), nd then rotating the mandrel further to the right until he ears 48 come to rest against the stop pins 32. As the nandrel 14 moves downwardly in the body 12, the camning surface 54 forces the locking dogs 16 radially outvard until they project through the ports 18 into an antular groove 58 in the housing 56, locking the packoff .0 into this housing 56.

As is readily apparent from the foregoing description, he packoif 10 is mechanically run and set, and thus there a no need for hydraulic lines or other cumbersome or xpensive manipulating means. A plurality of axially exending slots 60 in the upper end of the inside surface of he mandrel 14 provide access for pins on a conventional -type running tool (not shown) to the groove 44, facilitating installation and retrieval of the packoff 10 by such a tool and a drill string (not shown) to which it can be attached.

The locking dogs 16 serves to lock the packoff 10 in its housing against upward movement, the packoff body 12 being landed on a shoulder or other stop means 62 that prevents further downward movement of the device. Inner and outer annular resilient packing members 64 and 66, respectively, which can be single units as shown or a plurality of units, provide a pressure tight seal between the packoff, an inner casing string 68, and the outer housing 56, respectively.

As illustrated in FIGURES 4-6, the cross-sectional configuration of the packoffs correspond to the configurations of the various housings into which they are set, and with the various well tools that they might support or that might support them. For example, they can be shaped like the two packotfs 70 and 72, shown best in FIGURE 4, which are designed for use in a unitized wellhead such as that described in the aforementioned Todd application. As is readily apparent, the packoff 70 seals the annulus 74 between the unitized wellhead 78 and the first inner casing string 76, which could be the protection string, and the packoff 72 seals the annulus 80 between the wellhead 78 and the next inner casing string 82, which could then be the oil string. This sealing is effected through inner and outer packings diagrammatically illustrated at 84, it being understood that these packings 84 can be singular or plural, and of other configurations, all as desired.

In order to be able to monitor the pressure in the annuli 74, 80, and 85, the latter being located between the second inner casing or oil string and the production tubing 86, lateral ports 88, 89 and 90 are provided in the wellhead 78, and similar ports 91 (indicated by dotted lines) and 92 in the packotfs 70, 72, respectively. The ports 91, 92 in the packolfs 70, 72 do not have to be coaxial with the ports 89, 90 in the unitized wellhead 78, since the wellhead is provided with annular grooves 94, 95 that extend circumferentially and thus permit continuous fluid circulation between the ports 90, 92 and 89, 91, regardless of orientation of the packotls 70, 72. Another circumferential groove 96 in the packoffs 72 cooperates with the groove 95 to provide a larger passageway between the ports 90, 92 to accommodate fluids that might flow into or out of the annulus 85. Although they are not shown, conventional pressure or fluid conducting lines are attached to the outer ends of the ports 88, 89, 90 before the wellhead 78 is run.

As is shown best in FIGURE 4, both packoffs 70, 72 comprise bodies, mandrels, and locking dogs which cooperate with each other just as do their counterparts in the packoff 10. In packoff 70, the body 98 has a lower shoulder 100 which serves to support the packoff in the wellhead 78 when it is landed on the wellheads radially inward projecting seat 102, and an upper radially inward projecting surface 104 which provides a stop and seat for the mandrel 106. Except for a lower portion 108 that extends radially inward, thus providing a seat 110 upon which a well tool can be landed if desired, the mandrel 106 is shaped identically to the mandrel 14 in the packofi' 10, having ears 112 that cooperate with upper and lower annular grooves 114, 116, respectively, in the body 98, and a camming surface 118 and a locking surface 120 that activate the locking dogs 122, all in a manner analogous to the packofi 10.

The body 124 of packoff 72 has a lower portion 126 shaped to accommodate the annular space between the wellhead 78 and the casing 82, to provide a seat 128 for the production tubing hanger 130, and to provide a sealing surface 126a for a seal 129 on the hanger 130. However, the upper portion 132 of the body 124 is identical to the corresponding portion of the body 98 of the packoff 70. The mandrel 134 and the locking dogs 136 are shaped identically to their counterparts 106, 122, respective y, of packoff 70, so that the procedure for locking the packoff 72 into the wellhead 78 is the same as that for locking packolf 70 in this wellhead.

For purposes of illustrating the method of completing an OBS well according to this invention, attention is directed to FIGURES 47 of the drawings. As a brief background preparatory to describing this method, after the well is drilled and cased with OBS equipment, the conductor pipe and all of the casing risers between the ocean floor and the surface are removed and, using a J-latch running tool T (FIG. 7), a temporary abandonment cap 138 attached to a landing sub 140 is connected to a landing adapter 142 that has been left on the end of the oil string 82, a back pressure valve 144 is set in the cap 138, a temporary abandonment cover 146 is installed over the cap 138, and a corrosion cover 148 is then installed with a remotely controllable coupling (not shown) to the top of the conductor pipe (not shown) that extends into the ocean floor. As is evident from FIGURE 7, landing adapter 150 on the protection string 76 and landing adapter 152 on the intermediate string (not shown) are left in place when the well is abandoned. In the usual manner, each of the landing adapters 142, 150, and 152 have a pair of acme threads, one righthand and the other left-hand, so that right-hand rotation breaks the connection between the adapters and the risers (not shown), and makes up the tie-back subs -4, 156 and 158 (FIG. 6) into these adapters 142, 150, and 152, respectively.

With the foregoing brief background, the method for completing the well now will be described. First the corrosion cover 148 is removed and a unitized wellhead, such as 78, to which has been attached a casing extension or nipple 160 and tie-back sub 158, is landed on the intermediate string 162 by making up the tie-back sub 158 into the landing adapter 152. At this time, blow-out preventer equipment (not shown) and risers are installed to give total protection during the following completion procedure. The abandonment cover 146, the back pressure valve 144, and the abandonment cap assembly 138 and 140 are then removed in that order.

The protection string 76 (FIG. 6) is then extended into the wellhead 78 by an extension 164 that is connected to tie-back sub 156 which makes up into landing adapter 150 by right-hand rotation, and packoff 70 is then run and set between the wellhead 78 and the extended protection string 76. At this time, the annulus 74 between the wellhead 78 and the string 76 can be pressure tested via the ports 89, 91 to determine if a tight seal has been established by the packoff 70.

The oil string 82 then is extended into the wellhead 78 with extension 166 and tie-back sub 154 that is made up into landing adapter 142. Packoff 72 is run and set between the wellhead 78 and the extended oil string 82, and pressure tested via ports 90, 92 to assure that annulus 80 is sealed off.

The tubing string 86 with the tubing hanger 130 are run and landed on the seat 128, and a back pressure valve (not shown) is then run and set in the tubing hanger 130. The tubing hanger hold-down 168, having a body 170 like the upper portions of the bodies of the packofis 70, 72, a mandrel 172 identical to the mandrels 106, 134 and locking dogs 174 also identical to the dogs 122, 136, is run and set into the wellhead 78 using the same J-type running tool (not shown) and technique employed with the packoffs 70, 72, the hold-down 168 landing on an annular hold-down ring 176 that transmits the holding force from the hold-down 168 to the tubing hanger 130, securing it in place. A Christmas tree 178, such as that disclosed in the Lebeaux et al. US. Patent No. 3,050,126, containing a tubing hanger stinger 182, is landed on the wellhead 78 and then fastened to it by hydraulic or other remotely controlled couplings diagrammatically illustrated at 180, completing the well.

It is to be understood that although the foregoing description and the drawings show somewhat specific types of well equipment, such as the subs, adapters, unitized head, Christmas tree, etc., the inventive method can of course be carried out with other tools and equipment that perform or function in the same manner. Thus, the inventive method is of broad scope in that it does not depend upon use of precisely the same equipment disclosed herein.

As is evident from the foregoing, the method of this invention can be carried out entirely by remote control from the surface of the water. However, it should be understood that if for some reason diver assistance is desirable, such assistance can be employed within the spirit of the invention. For example, the Christmas tree could be mounted on the wellhead with conventional clamp-type connections or with conventional flanges, and these connections made by a diver. Therefore, the invention encompasses both techniques.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention as set forth in the appended claims.

Having completed a detailed description of the invention so that those skilled in the art could practice the same, I claim:

1. A method for completing anunderwater well by remote control from a surface location, said Well having been drilled and cased with ocean-bottom suspension equipment, comprising the following steps:

(a) running and landing a wellhead onto an outer casing string of the well at a subsurface location,

(b) extending the first inner casing string adjacent said Outer string into said Wellhead,

(c) sealing off the annulus between the said wellhead and the said first inner casing string,

(d) repeating steps (b) and (c) on all remaining inner casing strings, in consecutive order from the outermost to the innermost,

(e) running and landing at least one production tubing string into the said wellhead, and

(f) coupling a Christmas tree to the said wellhead and tubing string,

the performance of each of said steps (a), (b), (c), (d), and (e) being diver unaided and with mechanical means controlled remotely from a surface location.

2. The method of claim 1 wherein the performance of step (f) is diver-unaided.

3. The method of claim 1 wherein the said well has been temporarily abandoned prior to beginning step (a).

4. The method of claim 1 wherein the said well is newly drilled and cased.

References Cited UNITED STATES PATENTS 3,099,317 7/1963 Todd 166-.6 X 3,137,348 6/1964 Ahlstone 166.6 3,196,958 7/1965 Travers et a1 175--7 3,256,937 6/1966 Haeber et al 166-.6 3,299,951 1/ 1967 Todd 166.5 3,310,107 3/1967 Yancey 166.6 3,353,364 11/1967 Blanding 166-.5 3,421,580 1/1969 Fowler et al l66.6

CHARLES E. OCONNELL, Primary Examiner RICHARD E. FAVREAU, Assistant Examiner US. Cl. X.R. 175-7 I 

